(a) Field of the Invention
The present invention relates to a technology of accurately aligning various functional circuit layers with printing units to perform precision overprinting when simple electronic elements such as resistors and electrode circuits are precisely overprinted in the same pattern to be printed or a micrometer size electronic printing product where electronic circuits such as accumulators, diodes, transistors, and integrated circuits are multilayered is overprinted by a gravure offset rotary printer including a plurality of gravure offset rotary printing units.
(b) Description of the Related Art
The technology associated with the present invention is based on ‘a method and an apparatus for manufacturing an electronic element using a roll-to-roll rotary printing method’ filed by the applicant (Korean Application No. 10-2005-30722) and registered on Oct. 9, 2006 (Korean Patent No. 10-0634327).
In the registered patent, as illustrated in FIG. 3 of the present invention, a roll-to-roll rotary printing system for printing and manufacturing an electronic device having a multilayered functional ink layer structure by using a plurality of gravure offset printing units on one roll-to-roll rotary printer.
Such a roll-to-roll rotary printing printer employs a plurality of gravure offset type printing units which are not adopted in an in-line structure multicolor image printing. The printing units use a high resolution and a wide range of ink amount forming regulating capacity which are advantages of engravings in a gravure printing method and utilize a flexibility of a rubber itself and unique ink transfer characteristics on a surface of a rubber in a pad printing method, and thus are in charge of constituent circuit patterns of a three-dimensional electronic circuit element, respectively, to perform overprinting without destroying preceding ink layers. As a result, an electronic element can be collectively overprinted in one printer.
In general, in an alignment technology of realizing overprinting with a plurality of rotary printing units, one register mark is designated for each circumference of plate cylinder corresponding to the printing unit, respectively, and location of the register mark is verified per one rotation to correct location errors of the plate cylinders. An existing correcting method where a compensating roller is installed between printing units tends to develop to a sectional method as a plate cylinder recently starts to be driven in a direct drive method utilizing a servo motor. In any correction method, a traditional correction method of one rotation-one register mark is used. That is, one register mark is sufficient for alignment to a circumference of one plate cylinder. The correction method may be sufficient in image printing pursuing high-speed printing, but its precision is considerably insufficient in roll-to-roll rotary printing of an electronic element requiring a micrometer unit precision overprinting.
The reason why an overprinting precision in the one rotation-one register mark method is insufficient is that a location and a size of a printing line is changed in a micrometer level due to expansion and contraction of a film caused by various stress changes, such as printing pressure, dry heating, tension, and friction, which are inevitably applied while a thin roll printing film passes a plurality of printing units. Thus, in the one register mark per rotation method, an accurate arrangement is difficult even when complex prediction calculations and methods are utilized.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.